SM-6, Sea Venom, and Naval Strike Missile munitions were paired alongside a Mark 48 ADCAP torpedo to send the decommissioned Oliver Hazard Perry class frigate to the bottom of the Atlantic Ocean.
Concluding Exercise Atlantic Thunder 2026, the sink exercise (SINKEX) was conducted in the Northern Atlantic off the Outer Hebrides in Northern Scotland. The former USS Klakring, an Oliver Hazard Perry class frigate commissioned in 1983 and decommissioned in 2013, was specially prepared for the exercise with extensive cleaning and hazard removal.
The SINKEX was used to validate the capabilities of a number of new munitions which have entered service in recent years. Arleigh Burke class guided missile destroyer USS Paul Ignatius (DDG 117) fired an SM-6 missile in its secondary role as an anti-ship weapon, testing the performance of the missile towards the upper end of its range.
Decommissioned Oliver Hazard Perry-class frigate USS Klakring (FFG-42) being towed out of Philadelphia Naval Inactive Ship Maintenance Facility (NISMF) for SINKEX reportedly around Scotland – August 12, 2026 SRC: FB- Delaware River Shipping / John Curdy pic.twitter.com/y5JIvPBLVu
“Atlantic Thunder demonstrates the unmatched lethality and interoperability of the United States and United Kingdom,” said Captain Kelechi Ndukwe, Commander, U.S. Task Force 65. “This sinking exercise not only validated the power behind U.S.-UK offensive weapons but delivers a clear message to adversaries that the U.S. Navy and Royal Navy remain a ready allied force.”
New onboard SINKEX views — including some wild slo-mo
US-UK forces send the decommissioned guided-missile frigate USS Klakring to the bottom of the Atlantic
Blows delivered by USS Paul Ignatius, the newly commissioned USS Massachusetts, others
Royal Navy Type 23 frigate HMS Portland (F79) used the opportunity to conduct the service’s first ever ‘warshot’ launch of the Norwegian-built Naval Strike Missile (NSM) that has replaced the Harpoon in UK service. Petty Officer James Kenyon, an Above Water Warfare specialist on HMS Portland, said: “Being the first person to fire war-shot NSM and achieve a hit is a very proud moment, and one that will stay with me for the rest of my career. This was the culmination of over a year’s effort in planning and bringing the drills into service, and I am glad that I was able to contribute.”
Lieutenant Commander Louise Kirkaldy, Portland’s Principal Warfare Officer (PWO), said: “The successful firing of NSM marks a significant milestone for the Royal Navy, demonstrating our ability to deliver credible, modern maritime strike capability.”
HMS Portland launches a Naval Strike Missile during Exercise Atlantic Thunder off Scotland, striking the decommissioned USS Klakring in the Royal Navy’s first operational firing of NSM.
Portland’s contribution was added to by the ship’s embarked Wildcat helicopter, hailing from 815 Naval Air Squadron. In another first, the Wildcat fired a Sea Venom anti-ship missile at the Klakring in the first operational live firing of the weapon type against a realistic target.
A Wildcat helicopter can carry as many as four Sea Venom missiles per sortie, with each weapon packing a 120 kilogram warhead. Though much smaller than ship-killing weapons like NSM and Harpoon, the Sea Venom is designed to deliver enough destructive capability to destroy smaller naval vessels, or using multiple finely targeted missiles complete a successful mission kill against larger frigate or destroyer sized targets.
HMS Portland’s Wildcat Wildcat, prior to takeoff. | Source: LPhot Henry Parks/Crown Copyright 2026
Lieutenant Commander Rhydian Edwards, Test & Evaluation Commander, Maritime Aviation Strike Operational Advantage Group, said: “This was a landmark moment for the Wildcat Force. For the first time we demonstrated the live firing of an operational Sea Venom missile against a representative maritime target. More importantly, we proved our ability to execute the full maritime strike kill chain under realistic operational conditions.”
“This was about giving commanders confidence that Wildcat can find, fix and strike maritime targets using Sea Venom as part of a wider task group. The lessons learned from this activity will directly inform future tactics, training and operational capability development, ensuring Maritime Aviation Strike remains ready to fight and win when called upon.”
More air-launched munitions came in the form of guided bombs dropped by F-15E Strike Eagles based with the 48th Fighter Wing (FW) at RAF Lakenheath. P-8 Poseidon maritime patrol aircraft from the U.S. and UK also took part in the SINKEX, though no weapon launches have been attributed to them and their contribution may have simply been as surveillance platforms.
Finishing off the Klakring, the USS Massachusetts (SSN 798), commissioned into the U.S. Navy in March 2026, targeted the frigate with a Mark 48 Advanced Capability (ADCAP) torpedo.
USS Massachusetts (SSN 798) Virginia-class Block IV attack submarine leaving Faslane, Scotland – September 11, 2026 SRC: FB- Argyll Sea Glass pic.twitter.com/Ba4k7jzjyJ
Massachusetts, the 25th Virginia class submarine, was pushed into service without the traditional post-commissioning shakedown period in order to mitigate current shortfalls in U.S. attack submarine availability. The decision has been described as a ‘calculated risk’. The submarine was noted at the Royal Navy’s Faslane base earlier in September.
After U.S. forces at RAF Fairford rapidly stepped up security precautions yesterday, police have now confirmed that arrests have been made and residents evacuated in the adjacent village of Whelford as explosive ordnance disposal teams investigate a number of vehicles.
Following widespread reports on Sep. 26, 2026 regarding security levels at RAF Fairford – with spotters reporting alerts audible over the base’s Giant Voice tannoy system, aircraft being dispersed across the airfield, crash gates being blocked and reinforced, and an apparent rise in security level to FPCON Delta – we now have an indication as to the kind of imminent threat the base might have been preparing for.
BREAKING: Major incident declared and number of properties evacuated in Gloucestershire after men arrested on suspicion of offences under the Explosives Act.https://t.co/bvcwRBh8HPpic.twitter.com/lpBj6ePvEw
Whelford, a small village just outside RAF Fairford’s security fencing, has seen a large police presence descend and vehicles are investigated by British Army explosive ordnance disposal (EOD) teams. As a precaution, many local residents have been evacuated from their homes to a temporary emergency shelter established at a nearby leisure centre.
Gloucestershire Police, in an official statement, said: “A number of properties are currently being evacuated in the Whelford area following the declaration of a major incident. It follows the arrest of several men on suspicion of offences under the explosives act.”
“A cordon is currently in place but we’d like to reassure people that we believe this incident is contained,” the force added.
As well as Fairford, other U.S. bases in the UK – including RAF Lakenheath and RAF Mildenhall – have stepped up their own security. Yesterday, unusually, an air ambulance was even denied a requested transit across Mildenhall’s military air traffic zone (MATZ).
HELIMED 85, an Air Ambulance operated by East Anglian Air Ambulance, was denied transit through the Mildenhall MATZ this evening.
While U.S. military force protection condition (FPCON) levels are not directly advertised to the public, clues to them being changed can be seen from outside the fence, and occasionally the boards advising arriving personnel of the current FPCON level can be seen at entry/exit gates.
It is still unconfirmed, though very likely, that Fairford went to FPCON Delta – the highest level possible – while other bases like Lakenheath went to FPCON Charlie.
Another user on Facebook posts:
‘Can confirm base has apparently declared FPCON Delta, meaning highest threat level, civilians are told to stay clear of the base perimeter’ https://t.co/OAACqHD7CD
FPCON Delta is reserved for when an attack is deemed imminent or has just occurred. Entry to the base becomes limited to strictly essential personnel only, with ID and vehicle checks strictly enforced, while on the base personnel are effectively locked down to their specific place of work. FPCON Delta can sometimes be accompanied by an order to shelter in place.
Covering the situation last night, you could tell people were on edge.
Spotters were spooked upon hearing about the FPCON Delta.
I called the UK MOD for comment, they declined to issue the comment.
But the USAF did provide a statement – in essence they didn’t deny the reports… https://t.co/C6xXLsF6Fm
Though the investigation has only just begun, eyes will almost certainly first turn towards Iran, who said any base used to support Operation Epic Fury is seen as a valid target, including those in Europe. Fairford is still home to a forward deployed contingent of B-1B Lancer strategic bombers which, along with B-52 Stratofortresses, flew daily missions from the Gloucestershire airfield during the height of the U.S.-Iran War.
Munitions, including cruise missiles, could be seen being loaded onto the aircraft before departure to the south or southwest. They would then return after almost a full day in the sky.
Iranian agents are widely known to operate quite extensively on foreign soil, and previous arrests have been made in the UK of Iranian-linked individuals under the National Security Act. Other arrests have been made of Iranian nationals under the Terrorism Act.
In many cases, agents are thought to have arrived in their assigned countries through legal means – under work or student visas – in order to attract as little attention as possible. Homegrown agents with national citizenship can also be recruited, allowing them to operate even further below ‘radar’.
Earlier this month, we reported on a security alert at RAF Fairford following the surprise landing of a civilian business jet, though in that case all details were relatively quickly resolved and the landing established as accidental.
Update: Sept. 27, 1230 UTC (1330 local time)
Live camera feeds from news helicopters have documented activity by military EOD robots inspecting three vans in Whelford. One of these vans is marked with what is apparently fake branding for a fuel delivery company, displaying a mobile phone number which is not publicly linked to any such company.
This appears to be an L3Harris T7 explosive ordnance disposal robot. The max lifting capacity is 250lbs near the chassis with it’s single arm, and 60lbs at full extension.
It seems unlikely that the robot would be able to manipulate full barrels from the back of the van onto the… https://t.co/LzesC0GRRM
An image is also circulating purporting to show the arrest of several men by armed police (regular police in the UK are not routinely armed) early in the morning in Whelford. They appear shirtless, likely having been made to undress as a precaution against suicide vests.
Gloucestershire Police were due to deliver a press briefing before 1300 local time, but at the time of writing this has been delayed with no details as to when it will now happen.
Update: Sept. 27, 1300 UTC (1400 local time)
Gloucestershire Police’s short press briefing began shortly before 1400 local time, in which they confirmed five arrests had been made following an emergency call placed at 0045 regarding three suspicious vehicles near RAF Fairford.
Around 85 households have been evacuated inside the 400 metre cordon.
“Work to establish the full nature of this incident is ongoing,” a police spokesperson said. “We are in constant communication with our partners both locally and nationally, in particular we are working closely with our partners in counter-terrorism policing.”
The BBC live shot shows the proximity of the vans (red circle) to the base.
The five men have now been rearrested by counter-terrorism police on suspicion of the preparation of an act of terrorism. This rearrest (a formal measure – they had not been released from custody) means the expanded allowances of the Terrorism Act may now be applied, and the men are able to be detained for a longer period without being charged.
Confirmed: Armed officers arrested five men in the Whelford area on suspicion of committing offences under the Explosives Act. They were further arrested on suspicion of preparation of a terrorist act, contrary to section 5 of the Terrorism Act.
Under the Terrorism Act, suspects can be detained for up to 14 days without formally being charged with an offence. Usually detention without charge is limited to 24 hours, with extensions up to 96 hours allowed with judicial approval.
Update: Sept. 27, 1400 UTC (1500 local time)
A NOTAM has now been issued restricting airspace within a 4 nautical mile radius around the incident site to approved traffic only. News helicopters are now unable to gain a view of the scene.
The NOTAM reads:
RESTRICTED AREA (TEMPORARY) INSTALLED (WHELFORD, GLOUCESTERSHIRE) WI 4NM RADIUS OF PSN 514120N 0014527W. APPLIES TO ALL ACFT INCLUDING ANY SMALL BALLOON, ANY KITE, ANY UAS AND ANY PARACHUTE INCLUDING A PARASCENDING PARACHUTE OR PARAMOTOR. PILOTS ARE FORBIDDEN TO FLY WITHIN THE DESIGNATED AREA WITHOUT THE PERMISSION EMERGENCY CONTROLLING AUTHORITY GLOUCESTERSHIRE POLICE DRONE TEAM, CTC TEL 07966 516802. ATC UNITS CLOSE TO THE AREA ARE REQUESTED TO ADVISE AIRCRAFT ON THEIR FREQUENCIES OF THE CONTENTS OF THIS NOTAM. RESTRICTION OF FLYING REGULATIONS MADE UNDER ARTICLE 239 OF THE AIR NAV ORDER 2016.
It applies up to an altitude of 9,500 feet, and has a notional end date of Oct. 5 – though it could be cancelled before this date.
Update: Sept. 27, 1530 UTC (1630 local time)
Both UK Prime Minister Andy Burnham and U.S. President Donald Trump have commented on the unfolding events. Burnham, who wrote his statement on social media, said: “I know today’s incident near RAF Fairford will be deeply concerning for local residents and for many people following developments across the country. My thanks go to Gloucestershire Police, Counter Terrorism Policing, our Armed Forces and all those working to keep the public safe.”
I know today’s incident near RAF Fairford will be deeply concerning for local residents and for many people following developments across the country.
My thanks go to Gloucestershire Police, Counter Terrorism Policing, our Armed Forces and all those working to keep the public…
“I am especially grateful to those residents who have been asked to leave their homes while precautionary checks are carried out. The safety and security of the public is our first priority, and I want people to know that we will always take every step necessary to protect our communities and keep our country safe. The investigation remains ongoing, and I would urge people not to speculate while the authorities establish the full facts,” he added.
This is the first major security incident faced by Burnham’s government after he succeeded Keir Starmer as Prime Minister in July.
BREAKING: Donald Trump responds to the suspected bomb plot at RAF Fairford
“Working with Britain, it was an amazing job. We had them under investigation. They were looking to do big damage to our fort, and working with the British worked out great and we got them” pic.twitter.com/PlChiTQlSx
President Trump, who spoke informally to reporters after stepping down from Air Force One (notably a VC-25A) in Chicago, said: “Working with Britain, it was an amazing job. We had them under investigation. They were looking to do big damage to our fort [sic], and working with the British worked out great and we got them.”
This article concerns a developing story, and may be updated if and when new information becomes available.
Login
pic.twitter.com/y5JIvPBLVu
(@ArmchairAdml) 
(@MoloWarMonitor) 
(@WarMonitor3) 
PICTURED: The four men arrested over the major incident near RAF Fairford 
